Unassisted, the human eye can only see a limited portion of the electromagnetic spectrum, i.e., visible white light. Infrared light is invisible to the human eye but is detectable with electronic imaging sensors.
Head mounted night vision devices provide the ability to see in low-light conditions. Many night vision devices that are currently available gather existing low-level ambient light (e.g., from starlight) and then amplify the light through a chemical and electrical process that allows a user to see images in the dark. These night vision devices are typically enclosed systems that only allow the user to see the amplified image, and thus obstruct and limit the user's natural eyesight and field of vision. Also, because these night vision systems are designed for low or no light conditions, the functionality of the night vision devices is limited in brightly illuminated or mixed lighting conditions. Also, existing wearable night vision displays are expensive and can be bulky and cumbersome to wear.